Molecular weight analysis

The molecular weight analysis presented above is a purely thermodynamic result and is independent of any model. The procedure requires dilute solutions, but is not based on the assumption of ideality, even though Eq. (8.88) is a variation of the van t Hoff equation. 

The instrumentation of HdC, including a pump, an injector, a column (set), a detector, and a recorder or computer, is very similar to size exclusion chromatography SEC). The essence of this technique is the column. There are two types of HdC columns open microcapillary tubes and a nonporous gel-packed column. This chapter emphasizes column technology and selection and the applications of this technique on the molecular weight analysis of macromolecules. 

Polysaccharide Molecular Weight Analysis by Sedimentation Equilibrium... 

Table 10.1 Core-shell tecto(dendrimer) molecular weight analysis results obtained from MALDI-MS, AFM and PAGE.

Gel permeation chromatograms were generated from a Waters Associates, Inc. GPC equipped with a refractive index detector. The following operating conditions were employed mobile phase, THF flow rate 1 ml/min., columns ICP, 10, 500, 100 A . Sample concentrations were prepared at 0.2% (w/w) a 100 microliter aliquot was used for molecular weight analysis. Standard polystyrene samples (Polymer Laboratories, Inc.) were used to create a calibration curve. 

The detailed treatment of the molecular weight analysis of polymers is left to other texts. We should be aware that there are two types of molecular weights, number average and weight average. 

NM - Not measured - VPO molecular weight Analysis of Liquid Product Fractions low and high severity... 

Molecular weight analysis by MS is an essential analytical tool for the determination of disulfide connectivities of multiple-cystine peptides. MS analysis is applied in all the methods described above. Three types of MS analyses are presently used, FAB-MS, MALDI-MS, and ES-MS. The related methodology is developing rapidly and thus continuously increasing the analytical power of these techniques. 

The number average molecular weight analysis of the polymers obtained, gives values about twice those calculated from the amount of Bz2 Mg reacted (Table 1). 

Iverius, P. H. and Ostlund-Lindqvist, A. M. 1976. Lipoprotein lipase from bovine milk, isolation procedure, chemical characterization, and molecular weight analysis. J. Biol. Chem. 251, 7791-7795. 

Gel permeation chromatography of protein linear random coils in guanidinium chloride allows simultaneous resolution and molecular weight analysis of polypeptide components. Column calibration results are expressed in terms of a log M vs. Kd plot or of effective hydrodynamic radius (Re/). For linear polypeptide random coils in 6M GuHCl, Re is proportional to M0 555, and M° 555 or Re may be used interchangeably. Similarly, calibration data may be interpreted in terms of N° 555 (N is the number of amino acid residues in the polypeptide chain), probably the most appropriate calibration term provided sequence data are available for standards. Re for randomly coiled peptide heteropolymers is insensitive to amino acid residue side-chain composition, permitting incorporation of chromophoric, radioactive, and fluorescent substituents to enhance detection sensitivity. 

The technique described here is finding increasingly widespread use for the resolution and molecular weight estimation of naturally occurring polypeptides. Its intended function is to supplement the classical exact techniques of molecular weight analysis and is not intended as an alternative procedure. Although we are aware of no instance in which invalid data have been obtained, the method can only be considered an approximate one since measurement involves calibration with secondary standards, and at present it is not suitable for precise theoretical analysis. 

R.T. Swank and K.D. Munkres, Molecular weight analysis of oligopeptides by electrophoresis in polyacrylamide gel with sodium dodecyl sulfate, Anal. Biochem. 39 (1971) 462-477. 

Frechel and coworkers reported the hydrosilylation polymerization of the AB2 and AB3 carbosiloxy monomers 13, 14 and 15184-187. After polymerization in bulk, soluble polymers were obtained in 55-69% yields. Molecular weight analysis revealed the... 

Hydrosilylation is not the only reaction available for the preparation of hyperbranched poly(carbosiloxanes). In a recent report, Weber and Londergan described the preparation of hyperbranched poly(carbosiloxanes) by ruthenium-catalyzed addition of ortho C—H bonds across terminal double bonds (Scheme 26)190. Depending on reaction conditions, soluble or insoluble polymers could be obtained. NMR endgroup molecular weight analysis of the soluble polymer gave a value of 12,200. The structure of the polymer was established with XH, 13C and 29Si NMR analysis. 

I. Jardine. 1990. Molecular weight analysis of xotQms, Methods Enzymol. 193 441-455. (PubMed)... 

Lansing W. D. and Kraemer E. O. (1935) Molecular weight analysis of mixtures by sedimentation equilibrium on the Svedberg ultracentrifuge. J. Am. Chem. Soc. 57, 1369-1377. 

If the values of A, 6, and Dj are available, the molecular weight of a polymer can be directly determined from its retention time using Eq. (3). If Dj is not available, one may use a calibration curve [log DlDj) versus log M] constructed with a series of narrow polystyrene standards of known molecular weights. For the molecular-weight analysis of an unknown, the DlDj value of the sample is first calculated from its measured retention time, and then the molecular weight is determined from the calibration curve. 

The effects of Irradiation in the temperature range 20-200 C were assessed by molecular weight analysis and from the weight loss characteristics on subsequent thermal degradation. 

---